1) Most air conditioners work by compressing gas, cooling the gas back to ambient temperature, then letting the gas re-expand and cool adiabatically. Assume that it is a hot summer day in Maryland, 95 degrees F outside. If you want to cool this gas to 40 degrees F, by what factor to you need to compress the gas during the compression cycle? Assume that the gas being compressed is an ideal monatomic gas so =5/3.

2) Calculate the number density of CO₂ molecules in the atmosphere at the surface of Venus and Mars. How does this compare with the number density of N₂ molecules in the air that you are breathing?

3) Calculate the pressure scale height for the atmosphere on Venus. How far above the surface does the atmospheric pressure reach 1 bar? Assuming that the temperature profile follows the adiabatic curve, what is the temperaure at this altitude?

4) Explain why one can think of the Earth's surface temperature as being somewhat self-regulating over a range of temperatures, and not well regulated over a broader range of temperatures. Include in your discussion the Greenhouse effect and various factors controling the quantities of greenhouse gases in the atmosphere and ability of sunlight to penetrate the Earth's atmosphere.